High-voltage connector

ABSTRACT

A high-voltage power connector, and method of manufacture thereof, for use with plug-in modules, each section of the contemplated connector consisting of at least one central conductor and a shielding member coaxially disposed about the at least one central conductor and held in position by a dielectric disc which is so shaped as to eliminated areas of excessive electrical stress, the free ends of each conductor and shielding member being movable orthogonally to the dielectric disc so that when the modules are in their operating positions a shielded power connection is formed.

Unite States r en Dill et al. 5] Feb. 1, 1972 [54] HIGH-VOLTAGECONNECTOR 2,368,889 2/1945 Setterblade ..339/2Il X 72 Inventors: WilliamE. mu, Natick; Maurice G. La 32:3 :22 11322 gf fi' 4 2 3;

vault Ashland; Stanley L Kokoszka 1C 0 as Framingham; William W.Shrader, West I Newton, a of Mass Zrn utvy Ecamu erlsi4arvm A.lihsainplijon ssls ant xammer awrence aa Assignee: Raytheon Company,Lexington, Mass- Attorney-Philip J. McFarland and Joseph D. Pannone [22]Filed: May 18, 1970 [57] ABSTRACT [21] Appl. No.: 38,161

A high-voltage power connector, and method of manufacture thereof, foruse with plug-in modules, each section of the con- [52] "339/ 339/177 Rtemplated connector consisting of at least one central conduceld 0Search :1" 3 7 7 tor and a shielding member coaxially disposed about theat 3 l least one central conductor and held in position by a dielectric339/ 7 l 6 14 143 278 C disc which is so shaped as to eliminated areasof excessive R f n Cm! electrical stress, the free ends of eachconductor and shielding e ere mg l member being movable orthogonally tothe dielectric disc so UNITED STATES PATENTS that when the modules arein their operating positions a 431 412 7/890 S d 339/177 R shieldedpower connection is formed. tu te 2,778,995 1/1957 Gross et al. ..324/644 Claims, 2 Drawing Figures HIGH-VOLTAGE CONNECTOR The invention hereindescribed was made in the course of or under a contract or subcontractthereunder, with the Department of Defense.

BACKGROUND OF THE INVENTION This invention pertains generally to the artof making electrical connections between modules in an electrical systemand particularly to making high-voltage connections between suchmodules.

It is known in the art that high voltage interconnections betweenseparate modules may be made using conventional high-voltage connectortechniques, i.e., when there is sufficient spacing between modules,conventional threaded male and female connectors may be used. In certainapplications, however, where the spacing is limited, the size of therequired connectors militates against their use, especially if it isdesired that the modules be of the well-known plug-in" type. That is,plug-in modules of known construction may normally be used only in lowpower applications.

When high-voltage power connections are made in the vicinity ofradiofrequency equipment it is of the utmost importance that there be noradiofrequency interference with such radiofrequency equipment due tosuch connections. This means that a continuous radiofrequency shieldmust be provided to isolate the high-voltage power connections from theradiofrequency equipment.

It is also necessary that every plug-in connection be so designed andoperated that it remain free of corona. Although high-power connectorsof known design are satisfactory with respect to freedom fromradiofrequency interference and corona, such connections are, withoutexception, not easily made or broken. It follows, then, that suchconnectors are not adapted to use with plug-in modules.

Therefore, it is a primary object of this invention to provide ahigh-power connector for use with plug-in modules.

Another object of this invention is to provide a high-voltage connectorwhich does not require threaded male and female portions.

Still another object of this invention is to provide a highvoltage powerconnector for use with plug-in modules which does not allowradiofrequency interference with associated radiofrequency equipment.

A further object of this invention is to provide a high-voltage powerconnector which is free of corona during operation.

A still further object of this invention is to provide an improvedmethod for designing and fabricating a high-voltage power connector.

SUMMARY OF THE INVENTION These and other objects of this invention areattained by providing a pair of matching connectors, one for each moduleto be connected, each one of such connectors including a centerconductor and an electrical shielding member coaxially disposed withrespect to one another, the spacing therebetween being maintained by aninterpositioned dielectric disc having a cross-sectional shape such thatthe maximum electrical strength at any point thereon does not exceed thethreshold for corona discharge. The end of each center conductor andeach electrical shielding member is so formed and mounted that, when themodules to be connected are in place, the free ends of the two centerconductors and the two electrical shielding members make contact,respectively, with one another.

BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding ofthis invention reference is now made to the following description of aFIG. 2 is a crosssectional view of a matching pair of connectors,according to this invention, the two illustrated connectors being shownin position relative to one another just before seating.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, modules5,6 7 supporting, respectively, connectors 10, 12 are shown toillustrate the flexibility with which modules using power connectorsaccording to this invention may be mounted. Thus, letting module 5 be ahighvoltage power supply for a radar, module 6 be the modulator andmodule 7 be the radiofrequency power oscillator, it may be seen'thatdisconnection of any one of the three modules from either, or both, ofthe other modules may be accomplished by moving the module to bedisconnected in a direction as indicated by arrows a, b, c, d.Obviously, the modules 5, 6, 7 would each be mounted in guides (notshown) to permit motion in a desired direction. It will be observed, forreasons explained hereinafter, that upon disconnection the free end ofthe connector 10 simply moves out a short distance from the wall (notnumbered) of the module to which it is af-- fixed,'thus permitting themodule to be removed without interfering with adjacent modules.

Referring now to FIG. 2 it should be noted that the matching connectorsshown are in position just prior to their seating one against the other.That is, the modules on which the connectors 10, 12 are mounted are justshort of being juxtaposed. Therefore, the spring-loaded members of theconnectors 10, 12 are in their disconnected positions. Connector 10includes a ring 13 formed from the parent-conductive material of themodule wall. The ring 13 is formed so as to support a mushroomconfigured ring contactor l5. Springs 17 and retaining bolts 19 coactbetween the ring 13 and contactor 15 as shown to force the contactor 15to the left before the module is seated in its desired final position.Electrical contact is made between ring 13 and contactor 15 with leafsprings 16. The ring 13 also supports a dielectric disc in any desiredmanner. As shown here, it has been chosen to provide clamping elementshown generally at 23 which is bolted to the ring 13. It is noted herein passing that the clamping element 23 preferably is formed integrallywith the dielectric disc 21 so as to create a liquid seal as well as asupport for such disc. A circular opening (not numbered) is formedcentrally of the dielectric disc 21. Such disc is undercut as indicatedand an electrically conductive coating 27 is applied as shown. It ispreferred that the dielectric disc 21 be fabricated from high strengthporcelain although other materials such as polycarbonate, sometimesknown by the trademark of General Electric Corporation, LEXAN, glassfilled diallyn phthalate or aluminajmay be used. The leakage path acrossthe dielectric disc may, as shown on the left-hand side of thedielectric disc 21, be lengthened by forming concentric rings. A bushing29 is mounted in the opening in the dielectric disc 21. One end of thebushing 29 may be shaped in any desired manner to permit connection ofthe bushing 29 with the center connector 31 of a powercable. Forexample, here the right-hand side of the bushing 29 is beveled so thatthe complementary end of the center conductor 31 may be bolted to it asindicated. An electrical contactor 33, which generally has the shape ofa mushroom, is slidably mounted as shown in the bushing 29, there beinga helical spring 35 and a number of leaf springs 37 disposed between thestern of such electrical contactor and the bushing 29 to force theelectrical contactor 33 to the left in the Figure when the module is notseated and to permit current flow from the center conductor 31 to thecontactor 33 without passing through the helical spring 35. A stop 39,which may be threaded on the bushing 29 as indicated, holds theelectrical contactor 33 within the bushing 29 and serves as an oil seal.

The connector 12 is, except as will be now noted, identical withconnector 10. Thus, the ring 13' supports a number of leaf springs 41 inplace of the contactor 15. Each one of the leafsprings 41 may be affixedto the ring 13' in any convenient manner as, for example, by a retainingring 43 which is screwed onto the ring 13' in the manner illustrated.Each one of the leaf springs 41 is so dimensioned and positioned that itmay be deformed by the conductor 15 when the modules are juxtaposed. Theelectrical contactor 33 which is mounted on the bushing 29' as shown isfabricated from any desired electrical contact making material and mayas here shown be a simple spring-loaded button contact.

When the modules are juxtaposed the contactor 15 presses againstindividual ones of the leaf springs 41 and the electrical contactor 33presses against the electrical contactor 33, thus making connectionbetween the power cable in each module.

It should be noted here that the mating of the two connectors may beaccomplished by moving the two modules toward each other along a lineparallel to the axis of symmetry of connectors 10, 12 or by moving themodules relative to each other along a line perpendicular to such axis.In this latter mode of movement an automatic safety feature is inherentwhen the electrical contactor 33 presses against the leaf springs 41 todischarge lethal voltages.

While any one ofa variety of known design approaches may be taken todetermine the shape of the dielectric disc 13 for any particularapplication, it is preferred that the extrapolated Liebmann method asoutlined in Analysis and Computation of Electric and Magnetic FieldProblems, pg. 270, by K. J. Binns and P. J. Lawrenson, published byMacMillan Company, New York 1963, be followed. According to the Liebmannmethod, the design problem may be solved by specifying the boundaries ofthe various materials in the region of interest, the dielectricconstants of each and the voltages at the boundaries of the region ofinterest. Such information is then used to program a computer to lay outa resistance analog matrix of resistors wherein the value of eachresistor is inversely proportional to both the dielectric constant ofeach material and the distance from the axis of symmetry of theconnector. A typical matrix size is 48 80, but larger or smallermatrices may be used, depending upon the accuracy required of thecomputation. The voltage at each point of the matrix is then determinedin terms of the voltage at the adjacent four points. When an iterativeprocedure is followed it will be found that, after a number ofcalculations subsequent calculations change by a very small amount. Thefinal voltage matrix may then be used to determine the equipotentiallines across the dielectric disc. In a practical embodiment it should benoted that the equipotential lines across the dielectric disc should beas equally spaced as possible to avoid areas where the electric stresson the material of the dielectric disc may be in excess of the potentialat which a corona discharge may occur. After the equipotential lines arecomputed, the geometry of the dielectric disc, center conductor(s), andshield may be altered, and the calculation repeated.

Having described a preferred embodiment ofthis invention, it is evidentthat other embodiments incorporating its concepts may be used. Forexample, the shape of the central conductors may be changed if, forexample, it is desired to pass more than one powerline through theconnectors. Further, the shape of dielectric discs may be changed ifadielectric liquid is not used within either or both modules.

It is felt, therefore, that this invention should not be restricted toits disclosed embodiments but rather should be limited only by thespirit and scope ofthe appended claims.

What is claimed is:

1. High-voltage electrical power connectors for plug-in means formaintaining the maximum gradient of the electrostatic field between thecentral conductor and the shielding element at a value less than thevalue causing a corona discharge;

b. means for affixing the shielding element of each one of the matingcoaxial lines to a separate one of the plug-in modules to be connected;

or spring-loaded contact means mounted on the free end of one of theconductors and one of the shielding elements for completing a shieldedelectric circuit between the pair of mating coaxial lines when theplug-in modules are juxtaposed and,

d. the dielectric spacer in one of the mating coaxial lines being spacedfrom the corresponding dielectric spacer of the other one of the matingcoaxial lines when the plug-in modules are fully engaged.

2. High-voltage electrical power connectors as in claim 1, wherein thedielectric spacer is undercut adjacent to the central conductor, thearea undercut being covered with an electrically conductive glaze.

3. High-voltage electrical power connectors for plug-in modules as inclaim 1 wherein one surface of each one of the dielectric spacers isconvoluted and the second surface of each one thereof is substantiallyplanar for adapting such connectors to use when a dielectric liquidcovers the surfaces of the connectors within such modules.

4. High-voltage electrical power connectors for plug-in modulescomprising:

a. a pair of mating coaxial lines, each one thereof including:

i. a central conductor; and ii. a shielding element, such shieldingelement being concentric with the central conductor;

iii. a dielectric spacer, such dielectric spacer being disposed betweenthe central conductor and the shielding element, for maintaining thecoaxial relationship between the central conductor and the shieldingelement, the cross-sectional shape of such dielectric spacer varying tomaintain the maximum gradient of electrostatic field between the centralconductor and the shielding element at a value less than the valuecausing a corona discharge; and

iv. a chamber, such chamber being partially bounded by the shieldingelement and the dielectric spacer;

b. means for affixing the shielding element of each one of the matingcoaxial lines to a separate one of the plug-in modules to be connected;and

c. spring-loaded contact means, mounted on the free end of one of theconductors and one of the shielding elements, for completing a shieldedelectric circuit between the pair of mating coaxial lines when theplug-in modules are juxtaposed, such spring-loaded contact means beingmounted such that the volume of the chamber is invariant with therelative position of the plug-in modules.

1. High-voltage electrical power connectors for plug-in modulescomprising: a. a pair of mating coaxial lines, each one thereofincluding: i. a central conductor; ii. a shielding element concentricwith the central conductor; and iii. a dielectric spacer disposedbetween the central conductor and the shielding element for maintainingthe coaxial relationship between the central conductor and the shieldingelement, such dielectric spacer including means for maintaining themaximum gradient of the electrostatic field between the centralconductor and the shielding element at a value less than the valuecausing a corona discharge; b. means for affixing the shielding elementof each one of the mating coaxial lines to a separate one of the plug-inmodules to be connected; c. spring-loaded contact means mounted on thefree end of one of the conductors and one of the shielding elements forcompleting a shielded electric circuit between the pair of matingcoaxial lines when the plug-in modules are juxtaposed and, d. thedielectric spacer in one of the mating coaxial lines being spaced fromthe corresponding dielectric spacer of the other one of the matingcoaxial lines when the plug-in modules are fully engaged. 2.High-voltage electrical power connectors as in claim 1, wherein thedielectric spacer is undercut adjacent to the central conductor, thearea undercut being covered with an electrically conductive glaze. 3.High-voltage electrical power connectors for plug-in modules as in claim1 wherein one surface of each one of the dielectric spacers isconvoluted and the second surface of each one thereof is substantiallyplanar for adapting such connectors to use when a dielectric liquidcovers the surfaces of the connectors within such modules. 4.High-voltage electrical power connectors for plug-in modules comprising:a. a pair of mating coaxial lines, each one thereof including: i. acentral conductor; and ii. a shielding element, such shielding elementbeing concentric with the central conductor; iii. a dielectric spacer,such dielectric spacer being disposed between the central conductor andthe shielding element, for maintaining the coaxial relationship betweenthe central conductor and the shielding element, the cross-sectionalshape of such dielectric spacer varying to maintain the maximum gradientof electrostatic field between the central conductor and the shieldingelement at a value less than the value causing a corona discharge; andiv. a chamber, such chamber being partially bounded by the shieldingelement and the dielectric spacer; b. means for affixing the shieldingelement of each one of the mating coaxial lines to a separate one of theplug-in modules to be connected; and c. spring-loaded contact means,mounted on the free end of one of the conductors and one of theshielding elements, for completing a shielded electric circuiT betweenthe pair of mating coaxial lines when the plug-in modules arejuxtaposed, such spring-loaded contact means being mounted such that thevolume of the chamber is invariant with the relative position of theplug-in modules.